Clarify that TraceContext/Baggage propagators are required. (#1132)

open-telemetry · Oct 23, 2020 · c864922 · c864922
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diff --git a/specification/baggage/api.md b/specification/baggage/api.md
@@ -116,10 +116,13 @@ OPTIONAL parameters:
 `Baggage` MAY be propagated across process boundaries or across any arbitrary boundaries
 (process, $OTHER_BOUNDARY1, $OTHER_BOUNDARY2, etc) for various reasons.
 
-The API layer MAY include the following `Propagator`s:
+The API layer or an extension package MUST include the following `Propagator`s:
 
 * A `TextMapPropagator` implementing the [W3C Baggage Specification](https://w3c.github.io/baggage).
 
+See [Propagators Distribution](../context/api-propagators.md#propagators-distribution)
+for how propagators are to be distributed.
+
 Note: The W3C baggage specification does not currently assign semantic meaning to the optional metadata.
 
 On `extract`, the propagator should store all metadata as a single metadata instance per entry.

diff --git a/specification/context/api-propagators.md b/specification/context/api-propagators.md
@@ -312,8 +312,12 @@ Required parameters:
 The official list of propagators that MUST be maintained by the OpenTelemetry
 organization and MUST be distributed as OpenTelemetry extension packages:
 
-* [B3](https://github.com/openzipkin/b3-propagation)
-* [Jaeger](https://www.jaegertracing.io/docs/latest/client-libraries/#propagation-format)
+* [W3C TraceContext](https://www.w3.org/TR/trace-context/). MAY alternatively
+  be distributed as part of the OpenTelemetry API.
+* [W3C Baggage](https://w3c.github.io/baggage). MAY alternatively
+  be distributed as part of the OpenTelemetry API.
+* [B3](https://github.com/openzipkin/b3-propagation).
+* [Jaeger](https://www.jaegertracing.io/docs/latest/client-libraries/#propagation-format).
 
 Additional `Propagator`s implementing vendor-specific protocols such as AWS
 X-Ray (Note, AWS is used as an example, not as a requirement) trace header

diff --git a/specification/trace/api.md b/specification/trace/api.md
@@ -731,10 +731,13 @@ be called concurrently.
 
 ## Included Propagators
 
-The API layer MAY include the following `Propagator`s:
+The API layer or an extension package MUST include the following `Propagator`s:
 
 * A `TextMapPropagator` implementing the [W3C TraceContext Specification](https://www.w3.org/TR/trace-context/).
 
+See [Propagators Distribution](../context/api-propagators.md#propagators-distribution)
+for how propagators are to be distributed.
+
 ## Behavior of the API in the absence of an installed SDK
 
 In general, in the absence of an installed SDK, the Trace API is a "no-op" API.